Anyone who has traded for any significant length of time has been through it themselves at some point. They hit a good run of trading days and became so over-confident in their own trading abilities that they suddenly deviated from what's was working for them so far, broke their own rules in search of more "I can't possibly lose" trading opportunities, and quickly see what profits they had gained fly from their accounts. Or they took a string of losses and became frustrated with a market that is "working against them" and threw caution to the wind with undisciplined trade after undisciplined trade to get their measure of revenge or in the hopes of scraping back to their previous account balance. Of course, both of these over-trading scenarios rarely leave a profitable result and only act to dig a deep hole in a trader's account that they now need to dig themselves out of.